Patent GB-499631-A (GB)
Title: Receiving perforator
IPC: H04L17/20
Filed: 1938-04-13
Abstract: 499,631. Type - printing telegraphy; selective punching mechanism. KLEINSCHMIDT, E. E. April 13, 1938, No. 11426. Convention date, May 7, 1937. [Class 40 (iii)] [Also in Group VIII] A telegraphic strip perforating receiver has its punches operated one at a time under the combined control of individual cams and a single common magnet. A shaft bearing five helically arranged punch operating cams 7-11, Fig. 1, a feed punch cam 12, a feed cam 13 and a contact cam 66, is rotated through a slipping clutch 5 by a shaft 2 driven synchronously with the transmitter. In the normal condition of the line, a steady current flows through a receiving magnet 42 causing it to attract an armature 46 carried on a lever 43 pivoted on a stud 44. The start signal is a no-current condition and allows a latch 51 to drop off a bar 48 carried on the lever 43. This latch forms one arm of a two-armed lever 50, the other arm of which carries a detent 52 and finger 53 which co-operate with a projection 56 and resetting lug 57 respectively carried by a plate 14 fixed to the cam-shaft. Thus each time the lever 43 is released by a start signal, the cam-shaft is allowed to make a single revolution. Five punch-operating levers 15- 19, co-operating with cams 7-11, have central elongated apertures through each of which passes a stud 20 and are held in a raised position against a stud 21 by springs 22. When a current impulse is received, the movement of the lever 43 brings a bevelled plate 47, carried by it, under projections 58 formed in the levers 15-19. In this condition, when a lever 15-19 is depressed by its cam 7-11, it pivots about this plate 47 and raises its appropriate punch 23-27 against the action of one of the springs 30, so perforating the paper strip 28. When an impulse is a no-current condition, the plate 47 does not engage the projections 58 and the levers 15-19 are merely depressed about the lower ends of the punches without operating them. At the end of each revolution of the cam-shaft, the detent 52 is reset by the lug 57 and the shaft is held until the receipt of the next starting impulse. A feed punch 31 is operated once per revolution of the camshaft by the cam 12 and the feeding operation is performed by a toothed wheel 34 on a shaft 35 rotated intermittently by a ratchet 36 and pawl 37 operated by a cam 13 through a lever 38. Advancing tape at end of message. At the commencement of each revolution of the camshaft, a cam 66 raises a lever 65 to latch it on the top of a T-shaped lever 64 and to close contacts 70 mounted above it. These are in series with contacts 79 closed by the tilting of the lever 38 at the end of each revolution. During the receipt of signals at least one of the punch-operating levers 15-19 actuates a punch and this movement is utilized to raise a common arm of a lever 61, pivoted on the stud 20, the other end of which depresses the centre arm of the T-shaped lever 64 so unlatching the lever 65 and opening the contacts 70. Thus, the two contacts cannot be closed together. At the end of a message, five no-current impulses are received, none of the punches is operated, the contact 70 remains closed and both contacts are closed together momentarily when the cam 13 operates the lever 38. This completes a circuit through a battery 80, Fig. 4, and a magnet 71 causing it to step a ratchet 74 forward one tooth and by raising an arm 76 allowing contacts 77, 78 to close. These contacts bridge the receiving magnet 42 preventing it from attracting its armature on the return to normal line conditions. The cam-shaft is therefore free to continue rotating and at each revolution the contacts 79 close momentarily, stepping the ratchet 74 forward until the arm 76 again opens the contacts 77, 78 allowing the receiving magnet 42 to be energized and stopping the cam-shaft. Thus, in response to the five no-current impulses, the tape is automatically fed out a definite amount at the end of a message.